The present invention relates to a vehicle suspension system including two lateral links extending in the widthwise direction of a vehicle body and a trailing link extending longitudinally of the vehicle body.
As disclosed in the Japanese Patent Publication Gazette No. 62-56001, the conventional suspension system includes a wheel support member for supporting rear wheels revolvably, a front lateral link extending in the widthwise direction of the vehicle body, connected at one end to the vehicle body and the another end to the front side of the wheel support member, a rear lateral link extending in the widthwise direction of the vehicle body, connected at one end to the vehicle body and the another end to the rear side of the wheel support member, and a trailing link extending longitudinally of the vehicle body, connected at the front end to the vehicle body and the rear end to the wheel support member.
In this suspension system, since the intersecting point of the extended line of rotary axes of both the front and the rear lateral links to the wheel side is positioned to the rear of the rotary axis of the rear wheels, when an 22 ternal force, i.e. a lateral force, is received by a rear wheel (an outer wheel of steering) at cornering, a moment force is occurred to move the wheel support member to the rear, having the intersecting point of both the rotary axis of lateral links positioned to the rear of the revolving shaft of the wheel as a supporting point. The front lateral link swings to the rear of the vehicle body as if it brings the front part of the wheel support member inboard with respect to the vehicle, having the end portion on the vehicle body side as a supporting point. On the other hand, the rear lateral link swings to the rear of the vehicle body as if it brings the front part of the wheel support member into outboard, having the end portion on the vehicle body side as a supporting point. Thus, the toe angle is controlled by the lateral force at cornering of a vehicle to make rapid toe-in of rear wheels, and the roll understeer for higher stability of a vehicle may be obtained (refer to the Japanese Patent Application Laying Open Gazette No. 60-80946).
In stead of disposing the front and the rear lateral links in the above fashion, another conventional art for enhancing toe-in of the wheels, when receiving a lateral force at cornering of a vehicle, by changing the rigidity of the elastic bushing at the end portion on the vehicle body side or at the end portion on the wheel side of both lateral links has been known.
However, in the above conventional arts, when the lateral force is received by the rear wheel at cornering of a vehicle, the wheel is displaced to toe-in and roll understeer is promoted even at the initial stage of cornering of a vehicle. Thus, the rapid cornering at the initial stage of cornering gets worse.